The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
This invention relates to an apparatus and method for propelling a submersible through water. More particularly, this invention is to an apparatus and method for efficiently propelling a submerged craft that virtually eliminates wake drag effects.
Marine engineers continue to create designs that more efficiently propel objects and vehicles through the water, particularly as fuel costs rise. These propulsion systems should also produce the smallest residual environmental effects since large wakes produce undesirable far-reaching consequences on shoreline structures and marine habitat.
From a tactical standpoint, another important design consideration is the reduction of detectability of a propulsion system and its support vessel by an adversary. Previous marine propulsion methods make use of propellers, ducted propellers, impellers, and vectored jets of water. Propellers produce large amounts of in-water noise and are also fairly inefficient in propelling an object through the water. As the propeller blades move transiationally through the water, they expose the surface area of the propeller to the water flow external to the vessel""s hull and create unwanted drag. Contemporary water-jet systems and impellers produce jets of water behind the craft for forward thrust that can be vectored for steering. However, these jets are inefficient and generate great amounts of noisy scatter-turbulence rearward of the moving craft.
Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for an underwater propulsion system using multiple concentrically located jets of water that are pointed to flow coaxially and asymptotically along the surface of a hull of tapering elliptic, hyperbolic, or parabolic curvature (with K (p) greater than 0, K (p) less than 0, and K (p)=0 (but S(p) ‡0), respectively) or similarly tapering curved hull that approaches a parallel flat plane (with K(p)=0, S(p)=0) at its end where the jets of water roll off the hull to induce efficient vortex wake effects, over the hull and past the hull, that optimize flow efficiency of a submerged craft being propelled through the water.
An object of the invention is to provide a more efficient marine propulsion method and system for submerged craft.
Another object of the invention is to provide more efficient underwater propulsion that virtually eliminates the wake drag effects produced by conventional systems being propelled through the water.
Another object of the invention is to provide a marine propulsion method and system using vortex flow to increase propulsion efficiency.
Another object of the invention is to provide a marine propulsion method and system enhanced concentric vortexes on a hull.
Another object of the invention is to provide a marine propulsion method and system powered internally in the hull to permit water-jet vectoring without the need for external control surfaces that otherwise create drag and reduce propulsion efficiency.
Another object of the invention is to provide a marine propulsion method and system having the ability to vector a craft by controlling internal water-jets and utilize more efficient exterior hull shapes.
Another object is to provide a marine propulsion method and system creating a virtually non-existent wake.
Another object of the invention is to provide a marine propulsion method and system using multiple jets of water that are pointed to flow coaxially and asymptotically along the surface of a hull of tapering elliptic, hyperbolic, or parabolic curvature (with K (p) greater than 0, K (p) less than 0, and K (p)=0 (but S(p) ‡0), respectively) or similarly tapering curved hull that approaches a parallel flat plane (with K(p)=0, S(p)=0) at its end where the jets of water roll off the hull to induce efficient vortex wake effects, over the hull and past the hull, that optimize flow efficiency of a submerged craft being propelled through the water.
These and other objects of the invention will become more readily apparent from the ensuing specification when taken in conjunction with the appended claims.
Accordingly, the present invention is to an underwater propulsion system and method that are more efficient and reduce vortex wake effects. A submersible has a cylindrically-shaped hull, a nose portion connected forward and a tapering elliptic, hyperbolic, or parabolic curvature surface portion aft coaxially symmetrically disposed around a common longitudinally extending axis. The tapered portion has a leading end essentially the same diameter as the hull and a symmetrical apex at its trailing end on the longitudinal axis. The tapered portion has symmetrical rounded lateral contours laterally disposed from the longitudinal axis and rounded longitudinal contours extending from the leading end to the symmetrical apex. A high-volume pump inside of the leading end creates volumes of pressurized water from ambient water. Equal-distantly-spaced-apart jets in a circumferential row extending around the tapered portion extend through it and point in an asymptotical relationship with a down slope surface of the tapered portion. The jets emit jetted water from the volumes of pressurized water to form a spinning toroidal vortex of swirling jetted water on the down slope surface of the aft tapered portion.